Search

LiBaPO 4 : Tb3+, Dy3+ phosphors were prepared via sol-gel method by using the stoichiometric amounts of lithium nitrate LiNO 3, barium nitrate Ba(NO 3) 2 and ammonium dihydrogen phosphate NH 4 H 2 PO 4 as base materials. Morphology by scanning electron microscopy (SEM), structure by X-ray diffraction (XRD), thermal properties by Differential thermal analysis (DTA)/Thermogravimetric Analysis (TGA) and structural characteristics by Fourier transform infrared spectroscopy (FT-IR) were investigated. This paper presents luminescence properties using spectra from radioluminescence (RL), photoluminescence (PL), cathodoluminescence (CL) and, thermoluminescence (TL) and the influence of RE dopants (Tb3+, Dy3+) on the luminescent behavior of LiBaPO 4. Computerized Glow Curve Deconvolution (CGCD) and Peak Shape Method were used to determine the kinetic parameters and the obtained results were evaluated. The RL results of un-doped LiBaPO 4 showed the presence of a well-defined peak at 417 nm and a weaker band around 685 nm. Strong emissions were detected in the sample doped with Dy3+ correspond to 4F 9/2 →6H j transitions. Blue, yellow and red emissions were observed with transitions of 4F 9/2 → 6H 15/2 , 4F 9/2 → 6H 13/2 and 4F 9/2 → 6H 11/2 , respectively. As for LiBaPO 4 : Tb3+, green emissions originated from the characteristic transitions (5D 3 → 7F J (j = 6–3) and 5D 4 → 7F J (j = 6–1)) of Tb+3 ion was seen. The RL, PL and CL spectra were identical, suggesting these green emissions. Dy3+ doped sample has three glow curves located at 72 °C, 145 °C and 204 °C, while the main temperature peak is measured at 240 °C for Tb3+ doped sample. Chromotographic studies of LiBa 0·98 PO 4 : Dy3+ 0.02 reveals that calculated x and y color coordinates (0.3122, 0.3233) are very close to the white light. • Dy3+ and Tb3+ doped LiBaPO 4 phosphors were successfully synthesized by sol-gel process. • XRD results of Tb3+ doped LiBaPO 4 ceramics showed that the single-phase is preserved. • Thermoluminescence, radioluminescence and SEM-CL analysis of LiBaPO 4 : Tb3+, Dy3+ phosphors were studied. • The Peak Shape (PS) method and the Computerized Glow Curve Deconvolution (CGCD) were used to estimate the kinetic parameters. [ABSTRACT FROM AUTHOR]

In this work, phosphor materials with the formula YAlO 3 were synthesized via sol-gel method by using the stoichiometric amounts of yttrium nitrate and aluminum nitrate as base materials. The obtained phosphors were doped/co-doped with Tb3+, Nd3+ rare earth ions and Mn2+ transition metal ion. For evaluating the influence of the dopants, the grain size and morphology of the samples by scanning electron microscopy (SEM) and the phase and crystallinity of the synthesized materials by X-ray diffraction (XRD) were investigated. Optical absorption spectra, photoluminescence (PL) and thermoluminescence (TL) were performed to determine a relationship the changing dopant on luminescence properties of YAlO 3. Moreover, the kinetic parameters namely activation energy (E), order of kinetics (b) and frequency factor (s) of the synthesized pure and doped materials were calculated using Computerized Glow Curve Deconvolution (CGCD) and Peak Shape Method for a better understanding of the optical properties that change with the doping process. Strong green emission was detected in the sample doped with Mn2+ correspond to 4T 1 (G)→6A 1 (S) transition. As for YAlO 3 : Nd3+, characteristic emissions originated from 4G 11/2 → 4I 9/2 (∼423 nm), 4G 9/2 → 4I 9/2 (∼460 nm) and 4G 7/2 → 4I 9/2 (∼540 nm) transitions were seen. The optical band gap of undoped sample was calculated as 2.79 eV and depending on the presence of Nd3+ and Tb3+ dopant ions this value was decreased to the range 2.46–2.56 eV. • Strong green emission was detected correspond to 4T1(G)→6A1(S) transition of Mn2+. • Nd3+ and Tb3+ dopant ions caused to decreasing to the optical band gap. • Tb3+ ion was improved the TL glow curve intensity. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate whether the non-invasive serum marker FibroTest–ActiTest (FT–AT) reliably predicts the histological stage of fibrosis and/or activity, and decreases the need for a liver biopsy. Twenty-five children with naïve chronic hepatitis B were analyzed for haptoglobin, α2-macroglobulin, apolipoprotein A1, bilirubin, γ-glutamyl transferase, and alanine aminotransferase activity, and the FT–AT scores were computed. FT–AT scores were compared with histological data. FT predicted insignificant fibrosis in 14/23 (61%) patients at a cut-off level of 0.31. Nine patients (36%) had significant histological fibrosis, but none were predicted by FT. There was no correlation between FT scores and histological stage of fibrosis ( r: −0.221, p = 0.228). All 4 patients with significant histological activity had corresponding significant activity in AT (100%). Fifteen out of the 19 patients (78.9%) with significant activity in AT had insignificant histological activity. At the cut-off level of 0.36, AT predicted insignificant activity in all 6 patients (100%). There was no correlation between AT scores and histological activity ( r: 0.245, p = 0.237). According to histological data, 12 patients were candidates for treatment, but FT–AT did not predict 3 of them (25%). FT–AT does not appear ready for use in detecting either the stage of fibrosis or activity in children with chronic hepatitis B. [ABSTRACT FROM AUTHOR]

Objective Although cutaneous leishmaniasis (CL) occurs mostly in the facial area, periocular involvement accounts for 2–5% of the facial lesions. CL lesions localized in the periocular region can easily be confused with various other diseases. The aim of this study was to examine the frequency of periocular involvement in CL in the Çukurova region of Turkey, as well as the clinical characteristics, diagnosis and methods of treatment of this disease. Methods Between December 1998 and December 2004, patients who were diagnosed with CL were evaluated prospectively with respect to periocular involvement. Results From the 2066 patients evaluated with CL, 2622 lesions were identified. In 59 (2.9%) of these patients, a total of 66 (2.5%) lesions were located in the periocular area. Thirty-two (48.5%) of these lesions were of the papular type, 15 (22.7%) the nodulo-ulcerative type, 10 (15.2%) the plaque type, and nine (13.6%) the nodular type. Dacryocystitis was identified in four patients with periocular involvement. Over the follow-up period, no ocular or periocular deformities or complications developed in these patients. Conclusion Patients suspected of CL should be evaluated and treated early in the course of their disease to prevent any permanent ocular or periocular deformities. [ABSTRACT FROM AUTHOR]

Three novel mixed ligand complexes of Ni(II), Zn(II) and Cd(II) with p-chlorobenzote and N,N-diethylnicotinamide were synthesised and characterized on the basis of elemental analysis, FTIR spectroscopic analysis, solid state UV-Vis spectrometric and magnetic susceptibility data. The thermal behavior of the complexes was studied by simultaneous TG-DTA methods in static air atmosphere and the mass spectra data were recorded. According to microanalytical results, formulas of complexes are C34H40N4O8ClNi, C34H40N4O8ClZn and C34H44N4O10ClCd. The complexes contain two moles of coordination waters, two moles p-chlorobenzoate and two mole N,N-diethylnicotinamide (dena) ligands per formula unit. In these complexes, the p-chlorobenzoate and N,N-diethylnicotinamide behave as monodentate ligand through acidic oxygen and nitrogen of pyridine ring. The decomposition pathways and the stability of the complexes are interpreted in the terms of the structural data. The final decomposition products were found to be as metal oxides. [ABSTRACT FROM AUTHOR]

Chromium substituted Mn nanospinel ferrites having the formula MnCrFeO (0.0 ≤ x ≤ 1.0) have been synthesized using the microwave-assisted combustion synthesis. The composition, structural, spectroscopic features of the products were studied by X-ray powder diffractometry (XRD), Fourier transform infrared spectroscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy. XRD investigations indicated the formation of single-phased cubic spinel structure for all products. Lattice parameters of the products represented the continuous decrease with increasing the substitution of Cr. The saturation magnetization of undoped sample appeared to be highest and as Cr concentration increases magnetization of the samples decreases. There is one reflection loss minimum in all doped samples at around 13 GHz with magnitude of −12 dB mechanism of which is explained by quarter wave cancellation model. [ABSTRACT FROM AUTHOR]